Childrens high chairs are well known, not only the type incorporating a tray for support of the child's plates, but also the type which are in effect long legged chairs. With the latter type, a child sits at a table in the normal way but lifted up to a height suitable for the child to eat comfortably from a plate on the table. In due course a child grows out of his high chair and yet is too small to sit comfortably on an ordinary chair.
At this stage the child is often sat on a cushion on an ordinary chair to lift him to a suitable height. However, this is seldom a convenient arrangement, in particular because the cushion tends to push the child too far forward or back, and the cushion may slip onto the floor. Also the cushion usually gets dirty from the child's sticky fingers.
British patent specification No. 971,253 describes an adjustable seat for a child for use in a car. It has telescopically adjustable legs for adjusting the height in the car at which the child is seated. However such telescopic adjustment is provided as an integral part of the seat. Telescopic adjustment cannot readily be introduced into an existing chair, which may have legs with a widely varying diameter and cross-section.
British patent specification No. 1,461,588 describes an adjustable furniture support which comprises upright members for housing wooden blocks on which rest the legs of a piece of furniture to be moved. The support is not connected to the piece of furniture in any permanent manner, rendering it unsuitable for a chair which is to be moved regularly.